Process for removing hair from hides.



GUSTAV MAAG, OF NEW YORK, N. Y.

PROCESS FOR REMOVING HAIR FROM HIDE-S.

Specification of Letters Patent.

Qatented Sept. 5, 191 15.

No Drawing. Application filed August 26, 1912, Serial No. 717,022. Renewed November 6, 1915. Serial No. 60,167.

To all whom it may concern Be it known that I, GUSTAV Mime, a subject of the German Emperor, and a resident of the city of New York, county and State of New York, have invented certain new and useful Improvements in Processes for Be.

moving Hair from Hides, of which the fol lowing is a specification. V

In the process of preparing hides for commercial use in the form of leather, it is an important initial step to remove from such hides the animal hair which they carry in their natural state. This process, as at present carried on, involves first a thorough soaking of the dried hides for one or more periods of about twenty-four hours according to the condition of the hides. This process is occasionally followed, where it is desired that the hides be plumped, by subjectingthem to the action of a very dilute caustic soda solution, after which the hides are again thoroughly washed. The wet hides thus prepared are then placed in vats where they are exposed to the action of lime, which has the effect apparently of destroying the cells at the root of the hair. After this lime treatment is applied the hair may be removed from the hide by friction. This process occupies a very long time and in some cases it has been found expedient to subject the hides not only to the lime treatment, but also simultaneously therewith to a treatment involving the use of a certain portion of sodium sulfid. The sodium sulfid acts destructively upon the hair at once. At best, however, these processes have resulted in the adoption of unhairing methods occupying about a weeks duration. It has been proposed in the past to unhair hides by the use of sodium sulfid alone, and while theoretically such a process would seem to be a practical one because sodium sulfid has the property of destroying or consuming the hair itself, its use has never been adopted on a commercial scale because of the deleterious effect which the sodium sulfid was found to exercise upon the hides.

I have discovered that the sodium sulfid process can be advantageously and commercially employed provided the treatment takes place under certain conditions. Briefly stated, I have discovered that if the wet hides are subjected to the action of a sodium sulfid solution substantially of 1.5 Baum at substantially 95 Fahrenheit in what is known as a mill, and if the quantity of such sodium sulfid solution employed, figured on a dry basis, is by weight about 10% of the weight of the hides, then the depilatory effect of the sodium sulfid will be complete, Whereas the destructive effect of the sodium sulfid upon the hides is practically inconsequential. The amount of dry sodium sulfid employed should not ordinarily be less than 9% or more than 11% of the weight of the wetted hides. A suitable solution may be made by dissolving one pound of sulfid of sodium in fourteen pounds of water. Hides when treated in this way can be completely denuded of hair in a period of time from approximately ten minutes to thirty-five minutes according to the nature of the hide. If I use a more dilute solution I find that the effect will be that the tough or thick hairs of the hide will be removed, but the finer hairs will not be taken off, the finer and more delicate hair appearing to have a greater resistance to a sodium sulfid solution than the stronger thicker hairs. If, on the other hand, I increase the strength of the sodium sulfid solution, the hide itself is very likely to be puckered up or otherwise injuriously affected in many ways. The discovery, therefore, that there is a particular strength of sodium sulfid solution which will have both the necessary qualities of a commercially useful depilatory preparation, to wit, the removal of the hair and a non-injurious effect upon the hide, lies at the foundation of this invention.

In order to adapt this discovery to com mercial operations I find further that the heavier hides require a longer exposure to this solution than the lighter hides, and that while a limited amount of over exposure of the solution does not injure the hides, it is for commercial purposes necessary to adopt some universal method applicable to any lot of hides, whether the same be constituted of heavy or light or mixed hides. I have accordingly found that the amount of sodium sulfid solution or degree of strength specified should bear the relation of 10% by weight (of the dry salt) to the weight of the wet hides as they come from the soaking.

A practical illustration of the process is as follows: A certain quantity of wet hides are weighed and the mill, which is a large rotating drum with agitators therein, is

supplied with a quantity of sodium sulfid solution of the strength of 1.5 Baum at 95 Fahrenheit, the quantity of the dry salt in solution being 10% by weight of the weight of the hides; the hides are then placed in the mill and for about forty-five minutes a thorough agitation of the hides and the liquid takes place. At theend of this period, the mill is opened to permit the liquid, which by this time has completely removed the hair of the hides, and is, in consequence, very dark in color, to flow out. The hides are then thoroughly washed or rinsed for the purpose of removing all of the residuary sulfid. I thus accomplish in a very short time what has heretofore taken about a week.

The strength of the sodium sulfid solution as given above is not subject to a great deal of variation. If the strength is reduced to 1 Baum, the action will not be satisfactory and the same is true if the strength be increased to 2 Baum, so that the operation is effected only within fairly narrow limits.

It is not practicable or feasible to operate with a solution of less than 125 Baum or above 1.75 Baum. The proportion between the quantity of liquid and the weight of the hides is, however, subject to a slightly larger range of variation. All of these variations are intended to be included in the scope of my claims because I realize that advantage may be taken of my discovery by ostensible variation of the proportions given.

In the following claims I intend to include any processes of the kind described in which the novel features of my invention are employed whether the same be precisely followed or made the subject of some relatively immaterial variation or addition.

Having thus fully described the invention, What I claim as new, and desire to secure by Letters Patent is 1. The process of removing hair from hides which consists in subjecting them to the action of a solution of sodium sulfid of a strength of substantially 1.5 Baum at substantially 95 Fahrenheit.

2. The process of removing hair .from hides which consists in subjecting them to the action of a solution of sodium sulfid of a strength of 1.5 Baum at 95 Fahrenheit, the quantity of sodium sulfid in said solution being substantially 10% by weight of the weight of the hides.

3. The process of removing hair from hides which consists in subjecting them to the action of a solution of sodium sulfid of a strength of l.5 Baum at 95 Fahrenheit, the quantity of said solution being 10% by weight of the weight of the hides and agitating the hides and solution during the period of treatment.

4. The process of removing hair from hides which consists in subjecting them to the action of a warm solution of sodium sulfid of a strength not less than 1.25 Baum or more than 1.75 Baum.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

v GUSTAV MAAG.

Witnesses:

JAs. H. GRIFFIN, M. C. RODRIGUEZ.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. 0. 

